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排序方式: 共有1146条查询结果,搜索用时 31 毫秒
961.
David Schlessinger Randy D. Little Diha Freije Fatima Abidi Ileana Zucchi Giovanni Porta Giuseppe Pilia Ramaiah Nagaraja Sandra K. Johnson Jae-Young Yoon Anand Srivastava Juha Kere Giuseppi Palmieri Alfredo Ciccodicola Vittorio Montanaro Giovanna Romano Amelia Casamassimi Michele D'Urso 《Genomics》1991,11(4)
Yeast artificial chromosomes (YACs) have recently provided a potential route to long-range coverage of complex genomes in contiguous cloned DNA. In a pilot project for 50 Mb (1.5% of the human genome), a variety of techniques have been applied to assemble Xq24–q28 YAC contigs up to 8 Mb in length and assess their quality. The results indicate the relative strength of several approaches and support the adequacy of YAC-based methods for mapping the human genome. 相似文献
962.
Pfeiffer Fatima; Sternfeld Lutz; Schmid Andreas; Schulz Irene 《American journal of physiology. Cell physiology》1998,274(3):C663
We haveinvestigated control mechanisms involved in the propagation ofagonist-induced Ca2+ waves inisolated mouse pancreatic acinar cells. Using a confocal laser-scanningmicroscope, we were able to show that maximal stimulation of cells withacetylcholine (ACh, 500 nM) or bombesin (1 nM) caused an initialCa2+ release of comparable amountswith both agonists at the luminal cell pole. SubsequentCa2+ spreading to the basolateralmembrane was faster with ACh (17.3 ± 5.4 µm/s) than with bombesin(8.0 ± 2.2 µm/s). The speed of bombesin-inducedCa2+ waves could be increased upto the speed of ACh-induced Ca2+waves by inhibition of protein kinase C (PKC). Activation of PKCsignificantly decreased the speed of ACh-inducedCa2+ waves but had only littleeffect on bombesin-evoked Ca2+waves. Within 3 s after stimulation, production of inositol1,4,5-trisphosphate [Ins(1,4,5)P3]was higher in the presence of ACh compared with bombesin, whereasbombesin induced higher levels of diacylglycerol (DAG) than ACh. Thesedata suggest that the slower propagation speed of bombesin-inducedCa2+ waves is due to higheractivation of PKC in the presence of bombesin compared with ACh. Thehigher increase in bombesin- compared with ACh-induced DAG productionis probably due to activation of phospholipase D (PLD). Inhibition ofthe PLD-dependent DAG production by preincubation with 0.3% butanolled to an acceleration of the bombesin-induced Ca2+ wave. In further experiments,we could show that ruthenium red (100 µM), an inhibitor ofCa2+-inducedCa2+ release in skeletal muscle,also decreased the speed of ACh-induced Ca2+ waves. The effect ofruthenium red was not additive to the effect of PKC activation. Fromthe data, we conclude that, following Ins(1,4,5)P3-inducedCa2+ release in the luminal cellpole, secondary Ca2+ release fromstores, which are located in series between the luminal and the basalplasma membrane, modifies Ca2+spreading toward the basolateral cell side byCa2+-inducedCa2+ release. Activation of PKCleads to a reduction in Ca2+release from these stores and therefore could explain the slower propagation of Ca2+ waves in thepresence of bombesin compared with ACh. 相似文献
963.
I-SceI-Induced Gene Replacement at a Natural Locus in Embryonic Stem Cells 总被引:4,自引:0,他引:4
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Michel Cohen-Tannoudji Sylvie Robine Andr Choulika Daniel Pinto Fatima El Marjou Charles Babinet Daniel Louvard Frdric Jaisser 《Molecular and cellular biology》1998,18(3):1444-1448
Gene targeting is a very powerful tool for studying mammalian development and physiology and for creating models of human diseases. In many instances, however, it is desirable to study different modifications of a target gene, but this is limited by the generally low frequency of homologous recombination in mammalian cells. We have developed a novel gene-targeting strategy in mouse embryonic stem cells that is based on the induction of endogenous gap repair processes at a defined location within the genome by induction of a double-strand break (DSB) in the gene to be mutated. This strategy was used to knock in an NH2-ezrin mutant in the villin gene, which encodes an actin-binding protein expressed in the brush border of the intestine and the kidney. To induce the DSB, an I-SceI yeast meganuclease restriction site was first introduced by gene targeting to the villin gene, followed by transient expression of I-SceI. The repair of the ensuing DSB was achieved with high efficiency (6 × 10−6) by a repair shuttle vector sharing only a 2.8-kb region of homology with the villin gene and no negative selection marker. Compared to conventional gene-targeting experiments at the villin locus, this represents a 100-fold stimulation of gene-targeting frequency, notwithstanding a much lower length of homology. This strategy will be very helpful in facilitating the targeted introduction of several types of mutations within a gene of interest. 相似文献
964.
Affinity precipitation is a technique that imparts selectivity to the widely used primary purification step of precipitation
of proteins from crude extracts. Hetero-bifunctional affinity precipitation involves use of reversibly soluble/insoluble polymers
that can be used as backbones to conjugate affinity ligands for specific separations. A variety of such polymers have been
reported in literature. In this work we report development of carboxymethyl cellulose (CM cellulose) as a cheap, readily available
and versatile reversibly soluble polymer system. Available CM cellulose as sodium salt could be quantitatively precipitated
from its aqueous solution in presence of about 50 mM calcium and 7.2% w/v polyethylene glycol-4000, and could be resolubilised
in the working buffer in absence of calcium, polyethylene glycol or both. Effectiveness of the CM cellulose-calcium-polyethylene
glycol system was demonstrated by purifying lactate dehydrogenase from porcine muscle extractusing covalently conjugated Cibacron
blue dye-ligand. By careful choice of conditions that suppressed non-specific interactions, the system was shown to be an
effective affinity precipitation polymer system inspite of the polyelectrolytic nature of CM cellulose. Up to 23 fold purification
of the enzyme from crude extarct was obtained in one single precipitation sequence.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
965.
Frederick H. Kasten L. Fatima R. Pineda Paul E. Schneider H. Ralph Rawls Theda A. Foster 《In vitro cellular & developmental biology. Plant》1989,25(1):57-62
Summary Cell culture is a valuable method of evaluating the biocompatibility of new dental materials. The purpose of this study was
to compare the in vitro biocompatibility of an experimental fluoride composite resin with fluoride and non-fluoride-releasing
materials currently available. The dental materials tested were: MQ Silicate (silicate cement), KETAC-CEM and FUJI (type II
glass ionomer cements), VISIO DISPERS (a light-cured, nonfluoridated, microfilled composite resin), and FR-17 (an experimental
fluoride-releasing composite resin). The Smulow-Glickman (S-G) human, gingival epithelial cell line, which exhibits semidifferentiated
characteristics, was used in the study as a test system. Biocompatibility was quantified by counting the viable cells per
unit area remaining after 24 and 48 h at two radial distances from cured specimens immersed in the cell culture medium. The
test materials were observed to be most toxic to cells nearest the materials. A Time-Distance Cytotoxicity Index (TDCI) was
calculated to relate the percentage of dead cells to viable cells at each diffusion distance for each exposure time compared
to a nontoxic control. The relative toxicity ranking of the materials tested based on the TDCI was VISIO DISPERS (91%), FUJI
(82%), FR-17 (30%), MQ Silicate (23%), and KETAC-CEM (10%), which exhibited the least toxicity. The cytotoxicity of the experimental
resin FR-17 was within the range of cytotoxicity of currently accepted restorative materials.
this study was supported in part by grant R01-DE04749 from the National Institutes of Health, Bethesda, MD, to H. R. R., and
by grant no. S07-RR05704-13 from the Biomedical Research Grant Program, Division of Research Resources, National Institutes
of Health, awarded to the Louisiana State University School of Dentistry. 相似文献
966.
DHEA, DHEA sulphate and androstenedione are C19 steroïds secreted by the adrenal cortex. These hormones with a weak androgen activity are precursors of estrogens and androgens. In human and other primates these hormones are produced in important quantities, even though, in domestic and laboratory animals, a few secretion is measured. In this survey, the androstenedione is quantified both in plasma and adrenal gland of young, prepubertal and adult rabbits and the castration effects on adrenal cortex histology are noted too. The absolute weight (AW) of the left adrenal gland is slightly higher than the right (p > 0.05) for all animals and the gland absolute weight (AW) for the adult rabbit is superior to the young and prepubertal rabitts (p < 0.05). The castration effect in adult increases the adrenal weight (p < 0.001). A zonation of adrenal cortex for young rabbits is observed. The zona fasciculata is important for young and prepubertal rabbits whereas, the zona reticularis is thicker for the adults. Thickness of glomerulosa, fasciculata and reticularis zonas increased with 6.55% (p > 0.05), 15.9% (p < 0.01) and 79.21% (p < 0.001) for the castred adult rabbits and histological modifications were observed in the zona reticularis. The plasma androstenedione is negligible for the young (0.060 ± 0.01 ng/mL), weak for the prepubertal (0.152 ± 0.03 ng/mL) and reaches (0.263 ± 0.03 ng/mL) for the adult. The androstenedione relative content (ng/100 mg of adrenal weight) is 2.90 ± 0.30; 4.54 ± 0.82 and 1.34 ± 0.36 for the young, prepubertal and adult rabbits. In this work, an increase of the androstenedione adrenal content is observed for the prepubertal rabbits, which could intervene in the process of puberty. 相似文献
967.
968.
Hayton K Gaur D Liu A Takahashi J Henschen B Singh S Lambert L Furuya T Bouttenot R Doll M Nawaz F Mu J Jiang L Miller LH Wellems TE 《Cell host & microbe》2008,4(1):40-51
Some human malaria Plasmodium falciparum parasites, but not others, also cause disease in Aotus monkeys. To identify the basis for this variation, we crossed two clones that differ in Aotus nancymaae virulence and mapped inherited traits of infectivity to erythrocyte invasion by linkage analysis. A major pathway of invasion was linked to polymorphisms in a putative erythrocyte binding protein, PfRH5, found in the apical region of merozoites. Polymorphisms of PfRH5 from the A. nancymaae-virulent parent transformed the nonvirulent parent to a virulent parasite. Conversely, replacements that removed these polymorphisms from PfRH5 converted a virulent progeny clone to a nonvirulent parasite. Further, a proteolytic fragment of PfRH5 from the infective parasites bound to A. nancymaae erythrocytes. Our results also suggest that PfRH5 is a parasite ligand for human infection, and that amino acid substitutions can cause its binding domain to recognize different human erythrocyte surface receptors. 相似文献
969.
Reddy KK Lefkove B Chen LB Govindarajan B Carracedo A Velasco G Carrillo CO Bhandarkar SS Owens MJ Mechta-Grigoriou F Arbiser JL 《Pigment cell & melanoma research》2008,21(4):451-456
Melanoma is a common malignancy which is poorly responsive to chemotherapy and radiation. One of the major reasons melanoma responds poorly to these modalities is constitutive expression of Akt, which protects against apoptosis. The antidepressant sertraline was found to be a potent cytotoxic agent against A375 human melanoma. To determine the mechanism by which sertraline kills melanoma cells, Western blot analysis of signaling molecules, including phosphorylated Akt, caspase 9 and phospho-p70 S6 kinase was performed. Finally, the effects of sertraline on A375 xenografts in mice were assessed. Sertaline potently inhibited the phosphorylation of Akt, and caused cell death through induction of endoplasmic reticulum in vitro. Sertraline monotherapy demonstrated activity against A375 xenografts in vivo. Akt is a major cause of resistance of melanoma to current therapy. Antidepressants are commonly used to prevent interferon-induced depression. Use of antidepressants that decrease Akt may improve the efficacy of interferon and other therapies against melanoma. Further studies are needed to elucidate whether sertraline acts as an Akt inhibitor in melanoma. 相似文献
970.
Arcuri HA Apponi LH Valentini SR Durigon EL de Azevedo WF Fossey MA Rahal P de Souza FP 《Protein expression and purification》2008,62(2):146-152
The Human Respiratory Syncytial Virus (HRSV) fusion protein (F) was expressed in Escherichia coli BL21A using the pET28a vector at 37 °C. The protein was purified from the soluble fraction using affinity resin. The structural quality of the recombinant fusion protein and the estimation of its secondary structure were obtained by circular dichroism. Structural models of the fusion protein presented 46% of the helices in agreement with the spectra by circular dichroism analysis. There are only few studies that succeeded in expressing the HRSV fusion protein in bacteria. This is a report on human fusion protein expression in E. coli and structure analysis, representing a step forward in the development of fusion protein F inhibitors and the production of antibodies. 相似文献